Joints

Joints Overview

• Joints enable complex body movements (e.g., running, playing guitar, swimming).

• Joint actions are more complex than mechanical machines.

• Flexible connective tissue allows for the movement of our rigid skeleton.

Key Definitions

• Joint: Also known as articulation.

• Arthrology: The study of joints.

• Kinesiology: The study of motion in the human body.

Types of Joints

• Three categories of joints:

  • Fibrous: Permit little to no movement.

  • Cartilaginous: Allow for limited movement.

  • Synovial: Enable a wide range of movement.

  • Synostosis: Union or fusion of adjacent bones.

Fibrous Joints

• Held together by dense irregular connective tissue, allowing minimal movement.

• Types:

  • Sutures: Found only between skull bones; provide strength and minimal movement.

  • Syndesmosis: Greater distance between bones; allows for small movements (e.g., interosseous ligaments).

Cartilaginous Joints

• Allow for little or no movement.

• Types:

  • Synchondrosis: Connection via solid cartilage (e.g., rib to sternum).

  • Symphysis: End of bones covered by hyaline cartilage with a fibrous disc (e.g., intervertebral discs).

Synovial Joints

• Characteristics:

  • Articular cavity between bones.

  • Articular capsule containing lubricant.

  • Articular cartilage covering bone ends.

• Allow for a varying degree of movement and decreased friction.

Anatomy of Synovial Joints

• Articular Capsule: Encloses joint cavity; composed of fibrous and synovial membrane.

• Synovial Fluid: Secreted by the synovial membrane; functions include lubrication and shock absorption.

• Accessory Ligaments: Support and stabilize joints (e.g., ACL, MCL).

Articular Discs

• Fibrous cartilage pads between joint surfaces; absorb shock and improve fit.

Factors Affecting Movement

• Structure and shape of bones.

• Tension of joint ligaments.

• Muscle arrangement and tension.

• Contact of soft tissues and hormones (e.g., relaxin during pregnancy).

• Disuse impacts flexibility and joint functionality.

Aging Effects on Joints

• Reduced synovial fluid production; thinner cartilage.

• Shortened, less flexible ligaments.

• Common degenerative changes.

Osteoarthritis

• Common arthritis type characterized by cartilage loss.

• Causes: aging, obesity, inflammation, previous injuries.

• Progressive disorder affecting large, weight-bearing joints.

Rheumatoid Arthritis

• Autoimmune disease attacking joint tissues, leading to inflammation and pain.

• Results in joint deformities if untreated.

Gout

• Excessive uric acid buildup leads to crystallization in joints.

• Common in extremities, particularly the big toe joint.

Sprain and Strain

• Sprain: Injury to ligaments without bone dislocation.

• Strain: Injury to muscles or tendons due to sudden force.

Treatment of Sprains and Strains

• PRICE Method: Protection, Rest, Ice, Compression, Elevation.